Firing control switch



Oct. 24, 1961 B. SCHLACHMAN FIRING CONTROL SWITCH Original Filed March 29, 1957 2 Sheets-Sheet 1 INVENTOR BENJAMIN .SGHLACHMA/V Oct. 24, 1961 B. SCHLACHMAN FIRING CONTROL SWITCH Original Filed March 29, 1957 2 Sheets-Sheet 2 FIG. 2

GUN

POWER SUPPLY POWER SUPPLY BENJAMIN SGI'ILACHMAN United States Patent 1 Clainx.,. (Cl. 200-16) (Granted under Title 35, US. Code (1952), see. 266) 'The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

The present invention relates to a machine gun feed er switch and thecombination of interlocking a gun mechanism and a feed mechanism electrically and more particularly to a feeder switch for synchronizing a gun or guns to the speed and cycle of a feed mechanism similar to that disclosed in United States Patent No. 2,857,813 to Elliot. This application is a division of United States Patent No. 2,901,945 dated September 1, 1959 granted to the presentiapplicant.

Before the present invention, the feed mechanism and the gun mechanism were operated independently of each other. Thus, thegun was a free running gun and as long as the feeder was feeding ahead of the gun, the gun would function properly. This firing arranement between the-guns and feeder had the disadvantage that if the feeder lagged the gun for just one round, the result was that gun stopped firing. This stoppage of the firing of a gun resulted in a stubbed round, bolt run under or bolt home empty in the gun. It is to be noted that a stubbed round with particular kinds of ammunition can be a very serious and a detrimental condition to personnel and equipment. The reason for the late 'feeding may be due to many things such as belt surge, loss of air pressure', momentary link jams, momentary slowness in ammunition boxes, low temperatures as caused by high altitude, and malfunction of the feeder itself due to worn parts.

' The present invention connects the gun and the feeder electrically together through a switch and overcomes the above-mention disadvantages by slowing the gun down to; the speed or rate of the feeder mechanism. t -An object of the present invention is the provision of firing a gun at a rate that the feeder operates up to the maximum rate of firing of a gun. v I

Another object is to provide the operation of a feeder switch upon the proper placing of a round in the feeder mechanism for firing.

A further object of the invention is the provision of making-charging 'of a gun unnecessary since there is always a round in the gun chamber.

A still further object of the invention is to increase the life expectancy of the feed mechanism and the gun. Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: FIG. 1 shows a perspective partially cutaway view of a preferred embodiment of the feed mechanism of the present invention;

FIG. 2 illustrates a cross-sectional view through the t cover of the feed mechanism of FIG. 1; and

receiver body.

piston-type mechanism mounted on the top of the gun Patented Oct. 24, 1961 "ice 1 group consisting of drive piston'.15, stationary piston 23,

bufier plate 26, valve stem 30,"valve seat 29, sear mechanism 33 through 45, drive slide subassembly 70 through 75, last round lock (not shown) and motor housing 47.

The drive subassembly 13, the driving component of the disclosed feed mechanism, is powered by an air pressure of 600 pounds per'square inch during operation supplied to the air inlet port 1011 from the planes air supply. It is mounted on the top of the cover (not shown) and operates at right angles to the center line of the gun.

The drive piston 15 changes the air pressure force into a reciprocating mechanical action, and operates at right angles to the gun center line."The piston has five machine collars 16, 17, 18, 1 9, and 20 including the end collars. The collar 16 at the open end of the piston has a notch 21 that fits a pin 73' on the drive slide subassembly 70. The notch is engaged by the slide to prevent rotation of the piston. Both collars 16 and 17 at the open end engage a crescent-shaped shoulder 74 on the drive slide to transmit the reciprocation action of the piston to the slide subassembly.

The stationary piston is hollowrto allow air to enter the inside of the drive piston. This action allows the drive piston to be 'returned at the end of its powered stroke. The steel stationary piston is fixed, the outer end 24 being securely retained by the butter plate 26, while the inner end 25 rides inside of the drive piston.

The buffer plate, containsan air passage and directs air pressure to the stationary piston for the return stroke of the drive piston. The butter plate acts as a support for the stationary piston retainer 27 and the three fiber bumpers 28. The reciprocating valve stem controls the inlet and exhaust pressure for the air drive. The valve stem is 10- cated in the upper part of the motor housing 47. The

outer end 31 is supported by the valve seat 29 on the drive stroke and by the bore, in the, motor housingon the return stroke. The inner end 32 of the valve stem is locked to the valve spring" housing 37. The valve stem is a machined steel rod fitted with a tapered valve nut on the outer end. The self-locking nut secures a T-section sealed to the end of the valve stem. The four fluted sections as at 30 on the valve stem adjacent to' the valve nut provides an 'air passage'from an inlet port ahead of the drive piston and also guides the-valve stem during the reciprocating action. V

During'the drive stroke, the inner diameter of the valve seat 29 provides anair seal that permits the air pressure to pass to the head 22 of the drive piston. 'During the return stroke, the 'exhaust pressure passes out through the opening end of the valveseat.

The scar mechanism-controls the movement of the valve stem 30 and also the operation of the feeder switch 50. The mechanism consists of a power sear 33, exhaust sear 34, sear spring 35, valve spring 36, valve spring housing 37, two spring retainer buttons 40, and a sear 'slide'41. Each sear is tripped by a cam projection 42 is a rectangular box-like piece that rides on the sear slide.

A projecting shoulder 39 on one side of the housing 37 is a stop for the'sears. Theinner end 38 of the housing is machined to fit the collar or inner end 32' of valve stem 30. The valve 30 and valve spring housing 37 are operated by the valve spring 36 located inside of the valve spring housing. Two movable spring retainer buttons 40 at each end of the valve spring 36 provide a surface for the sear slide lugs 43 to butt against during operation. Each sear is pivoted about its holding pin (not shown) that protrudes through the motor housing. A sear spring 35, pivoted between the sears, maintains a constant downward pressure on each sear at the extended arms of the sear spring. Two interchangeable steel bumpers 45, one at each end of the housing, have an arch cutout in the center providing a passage for the valve stem.

The feed switch assembly 50 which limits the firing rate of the gun to the rate of the feeder or feed mechanism comprises metal contacts 51 supported on the underside of the motor housing cover 48, contact buttons 52, compression springs 53, and contact button bushings 54. The motor housing cover has two longitudinal spaced undercut portions 55 wherein the metal contacts 51 are secured to a nylon support 56. The electrical metal contacts are spaced apart, each having an exposed surface in the same plane with one end thereof beveled. The nylon support secured to the metal cover has two parallel spaced apart ledges 57 in agreement with the spacing between the electrical contacts and the surfaces of the ledges in substantially the same plane as the surfaces of the contacts. The electrical contacts are insulated from the metal cover by a layer of insulating cambric 58 extending between the nylon support and the metal housing cover. The-wires 59 from an electrical fitting 60 are soldered and secured to the edge of the metal contacts opposite to that of the beveled end.

The valve spring housing 37 on the upper surface thereof has two openings 61, one at each end thereof for receiving a contact button bushing 54. The bushing as an insulating flanged well supports a compression spring 53 and a contact button 52. In operation, the metal contact button moves back and forth by pressing against the parallel spaced ledges of the nylon support and the spaced surfaces of the electrical contacts which thereby closes the electrical connection between the metal contacts.

The drive slide subassembly 70 changes the pneumatic driving force of the drive piston 15 into a mechanical force to operate the feed mechanism. The drive slide 71 is connected to the drive piston and transmits the reciprocating power of the drive piston to the drive pawls 72 in the bottom of the drive slide. The top of the drive slide is grooved to provide clearance for the drive piston.

A pin 73 and shoulder 74 at one end of the grooved portion 75, engage the notch 21 and collar 16, respectively, at the open end of the drive piston. The rectangular shape cover (not shown) supports and locks the drive assembly to the feed throat assembly.

The feed throat assembly partially shown strips the link 76 from the round 11, guides the stripped round 11 to ramming position in feeder throat 77 on top of the breechblock assembly 81 of the gun directly over the bolt 83, ejects the case from the gun, and holds the stripped round as the drive pawls 72 move to engage the link of the next round 12. The feed throat assembly fits on top of the gun receiver 80 with the lower section of the throat 77 extended into the gun receiver.

The external wiring diagram of a firing circuit for synchronizing two guns together having feeder switches is shown in FIG. 3. The elements on the left side of FIG. 3 are for gun No. 1 and on the right side for gun No. 2. In the gun. mechanism, the forward movement of the breechblock assembly actuates the firing pin into contact with the electric primer 92 A inch before the assembly reaches its full forward position, actuates through a'firing pin contact a connection between the firing pin and squib A A; inch from full forward position, and finally closes the connection by a slide contact between squibs B and C at its full forward position.

Explanation of the wiring diagram is now made ex- 4t cluding the feeder switches. Current is supplied to squib B of synchronizing switch 9% and to squib B of synchronizing switch Moving the breechblock of gun No. 2 into battery ahead of gun No. 1, the current flows from squib B through its breechblock slide contact 91 to squib C and then through conductor 96 to squib A of synchronizing switch 96 of gun No. 1. Gun No. l breechblock then comes forward, and the current supply to its synchronizing switch squib B is allowed to flow through to squib C. Simultaneously, the firing pin contact completes the circuit to its firing pin from squib C in gun No. 2 and the current from squib C in gun No. 1 flows through squib A of gun No. 2, allowing both guns to fire together. Since the feeder switch slows the firing of the gun down to the rate of feeding of the feed mechanism, the closing of synchronizing switch by the breechblock assembly is always ahead of the closing of the feeder switch. With the addition of two pole feeder switches 50 and St) to each gun between their respective power supplies 93 and 93', the firing of each gun is dependent upon the closing of both feeder switches.

From the inspection of the wiring diagram of FIG. 3, it can be realized that both gun No. l and gun No. 2 must fire simultaneously. As for an example, if both breechblocks of the guns, are in contact with their slide contacts 91 and 91' and if one feeder switch is in closed connection, then both guns are dependent upon closing of the second feeder switch. This means that the guns cannot fire any faster than the feeders are feeding the ammunition to the throat of the feeder mechanism or the receiver of the gun. In other words, the gun fires at a rate that the slow feeder operates to the maximum rate of the fire of the gun. The switch in addition prevents stubbed rounds and bolt home empty. By preventing stoppages, feeder parts life and some gun parts life are increased. In marginal feeders, every round is controlled by this switch, thus feeder stoppages of the gun are eliminated. At times, electrical arcing at the gun synchronizing contacts caused premature ignition of the gun gases. This disadvantage is now prevented since any arcing would now occur at the switch contacts 5 1 which is sheltered from the gun gases by the motor housing cover 48.

The operation would be as follows providing a round is in the chamber of the gun ready for firing.

The head 22 of the drive piston 15 is near the valve seat end of the motor housing and is in position to be powered for the drive stroke by the application of air pressure to the head end of the drive piston. The scar slide 41 is engaged by the end collar 16 of the drive piston. The valve stem 36 is in position to allow the inlet air pressure to flow to the head end of the drive piston. The power sear 33 is held in down position by the sear spring 35. The valve stem 3t) and valve spring housing 37 are locked in power position by the action of the power sear 33 abutting against shoulder 39 on the side of the valve spring housing. The drive slide 7 1 is in its extreme position at the ammunition feed intake side of the feed mechanism with the drive pawls 72 bearing against the ammunition link 76 holding the round. The breechblock 81 of the gun is in the full forward position.

At the start of the drive stroke, the drive piston 15 and the drive slide 71 are the only moving components. The drive slide moves from the ammunition feed intake to the link ejection side of the mechanism i.e., from left to right as viewed in FIG. 1. At the start of the drive stroke, the end collar 16 on the drive piston 15 no longer bears against the sear slide bottom lug 44. Approximately half way through the drive stroke,.the center collar 18 of the drive piston :abuts against the sear slide lug 44. The sear slide 41 now moves with the drive piston to the end of its stroke. By the movement of the sear slide with its projecting cam 42, the power sear 33 is engaged and started upward and the exhaust sear 34 is in position to move downwardly when it has passed over the shoulder 39 on the spring housing 37. The drive slide 71 continues to move whereby the round 11 is driven inward against an element (not shown) of the feed throat assembly and causes the round to change its direction of travel. As the sear slide 41 travels, a lug 43 on top of the sear slide abuts against a spring retainer button 4% which compresses the valve spring 36 supplying the force to shift the valve stem 30. Towards the end of the drive stroke, the sear slide cam 42 raises the locked power sear 33 s'uificiently to allow the spring loaded housing 37 to shift its position away from the valve seat. The valve stem and the spring housing thus move to the exhaust position. With the movement of the spring housing, the feeder switch contacts 51 are closed by button 52. The exhaust sear 34is forced downwardly by the sear spring 35 and locked against the shoulder 39 on the side of the valve spring housing. The valve stem 36' now has changed its position to exhaust the air used during the drive stroke to the atmosphere. The bottom lug 44 of the sear slide is abutting against the middle collar '18 of the drive piston and the sear mechanism is held in position by the locked exhaust sear 34. The drive slide 71 continues to move to the end of the drive stroke stripping the round 11 from the link 76. Thus, the switch is closed when the round is stripped from the link and consequently no further pull on the ammunition belt is required.

At the start'o f the return stroke, the middle collar 18 of the drive piston ceases to bear on the bottom sear slide lug 44 and the sear slide 41 remains stationary. The drive slide subassembly 70 and drive Piston 15 actuated by the air pressure through the buffer plate 26 and stationary piston 23 are the only moving components of the drive subassembly. The feeder switch remains closed during the first part of the return stroke while the round is pushed into the feed throat 77 until the round rests on the breechblock. This is the first temporary stalled position. This stalled condition is transmittedthrough the feed throat assembly to stop the movement of the drive slide and the drive piston. When the round in the chamber of the gun is fired, the breechblock is forced to the rear and the round in the throat of the feeder is in the ramming position ready to be picked up by the breechblock on its forward movement. The feeder mechanism is temporarily stalled a second time until the round in the throat has been picked up by the breechblock.

Approximately half way thorugh the return stroke the bottom sear slide lug 44 is engaged by end collar 16 on the drive piston, the sear slide then moves with the piston to the end of the return stroke. The scar action is similar to that for the drive stroke except that the spring loaded housing shifts in the opposite direction. The shift of the valve spring housing changes the position of the valve stem so that the exhaust port is sealed and the inlet pressure is again allowed to go to the head end of the drive piston. The exhaust sear 34 has been raised up by the cam 42 on the sear slide 41 and the power sear 33 has been pressed downwardly by the sear spring to lock the spring housing 37 in the power position. By this movement of the spring housing, the feeder switch is now open. The drive slide continues to move to the ammunition feed intake side of the mechanism so that at the end of the return stroke the drive slide 71 is in position to pick up the next round 12. It is to be noted that the feeder switch is only in closed position when the round is stripped from its link and ready to be pushed downwardly into the throat.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. For example, if one wanted to control the firing of a single gun alone, then a one pole switch could be placed in the firing circuit of this single gun. It is therefore to be understood that within the scope of the appended claim the invention may be practiced otherwise than as specifically described.

What is claimed is:

Switch means (for a gun feed mechanism comprising a flat metal plate having two longitudinally spaced recessed portions therein, each recessed portion having a contact support, each contact support having two spaced longitudinally extended ledges and two spaced metal contacts secured to said support in parallel with said ledges, an insulating fabric between said contact support and said metal plate for insulating said metal contacts from said metal plate, said contacts each connected to a wiring conductor, and a contact button for each recessed portion adapted to slide along the ledges of said support onto said spaced metal contacts thereby closing the electrical connection between said spaced metal contacts.

References Cited in the file of this patent UNITED STATES PATENTS 1,248,375 Morrison Nov. 27, 1917 

